CA2451760C - Reduced sensitivity, melt-pourable tritonal replacements - Google Patents
Reduced sensitivity, melt-pourable tritonal replacements Download PDFInfo
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- CA2451760C CA2451760C CA002451760A CA2451760A CA2451760C CA 2451760 C CA2451760 C CA 2451760C CA 002451760 A CA002451760 A CA 002451760A CA 2451760 A CA2451760 A CA 2451760A CA 2451760 C CA2451760 C CA 2451760C
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- C—CHEMISTRY; METALLURGY
- C06—EXPLOSIVES; MATCHES
- C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
- C06B31/00—Compositions containing an inorganic nitrogen-oxygen salt
- C06B31/02—Compositions containing an inorganic nitrogen-oxygen salt the salt being an alkali metal or an alkaline earth metal nitrate
- C06B31/12—Compositions containing an inorganic nitrogen-oxygen salt the salt being an alkali metal or an alkaline earth metal nitrate with a nitrated organic compound
- C06B31/14—Compositions containing an inorganic nitrogen-oxygen salt the salt being an alkali metal or an alkaline earth metal nitrate with a nitrated organic compound the compound being an aromatic
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- C—CHEMISTRY; METALLURGY
- C06—EXPLOSIVES; MATCHES
- C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
- C06B21/00—Apparatus or methods for working-up explosives, e.g. forming, cutting, drying
- C06B21/0033—Shaping the mixture
- C06B21/005—By a process involving melting at least part of the ingredients
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- C—CHEMISTRY; METALLURGY
- C06—EXPLOSIVES; MATCHES
- C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
- C06B29/00—Compositions containing an inorganic oxygen-halogen salt, e.g. chlorate, perchlorate
- C06B29/22—Compositions containing an inorganic oxygen-halogen salt, e.g. chlorate, perchlorate the salt being ammonium perchlorate
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- C—CHEMISTRY; METALLURGY
- C06—EXPLOSIVES; MATCHES
- C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
- C06B31/00—Compositions containing an inorganic nitrogen-oxygen salt
- C06B31/28—Compositions containing an inorganic nitrogen-oxygen salt the salt being ammonium nitrate
- C06B31/32—Compositions containing an inorganic nitrogen-oxygen salt the salt being ammonium nitrate with a nitrated organic compound
- C06B31/38—Compositions containing an inorganic nitrogen-oxygen salt the salt being ammonium nitrate with a nitrated organic compound the nitrated compound being an aromatic
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Abstract
This melt-pourable explosive composition shares comparable explosive properties to those of Tritonal and is melt-pourable and castable under conditions comparable to those of Tritonal, but experiences equal or less impact, shock, and thermal sensitivity and avoids the issues of toxicity associated with trinitrotoluene. The trinitrotoluene component of Tritonal is replaced with one or more mononitro aromatic and/or dinitro aromatic melt-pourable binders, such as dinitroanisole, which can be melt poured without presenting the toxicity drawbacks experienced with the use of TNT. The melt-pourable binder can also be combined with a processing aid selected from the group consisting of alkylnitroanilines and arylnitroanilines. The composition also includes oxidizer particles, which are preferably inorganic oxidizer particles, and reactive metallic fuel, such as aluminum.
Description
68483-40(S) REDUCED SENSITIVITY, MELT-POURABLE TRITONAL
REPLACEMENTS
BACKGROUND OF THE INVENTION
1. Field of the Invention This invention relates to explosives, and in particular this invention relates to explosives that are melt-pourable and may function as excellent replacements for Tritonal. In a particularly preferred aspect, this invention relates to Tritonal replacement compositions that exhibit similar melting characteristics, comparable energetic performance, and either comparable or reduced shock and thermal sensitivities to Tritonal. This invention also relates to mortars, grenades, artillery, warheads, and antipersonnel mines containing the melt-pourable Tritonal replacement compositions.
REPLACEMENTS
BACKGROUND OF THE INVENTION
1. Field of the Invention This invention relates to explosives, and in particular this invention relates to explosives that are melt-pourable and may function as excellent replacements for Tritonal. In a particularly preferred aspect, this invention relates to Tritonal replacement compositions that exhibit similar melting characteristics, comparable energetic performance, and either comparable or reduced shock and thermal sensitivities to Tritonal. This invention also relates to mortars, grenades, artillery, warheads, and antipersonnel mines containing the melt-pourable Tritonal replacement compositions.
2. Description of the Related Art The melt-pourable explosive composition Tritonal usually consists of 60-80 weight percent 2,4,6-trinitrotoluene (TNT) and 20-40 weight percent aluminum (AI). Tritonal has been used in a wide array of military applications, although perhaps its most frequent use is as a general bomb fill. One of the reasons for the wide acceptance of Tritonal is that its binder component, TNT, has a relative low melting point of 81°C, which makes Tritonal suitable for pouring into shells or casings of munitions.
However, Tritonal has several drawbacks attributable to its TNT binder.
One of the most prominent of these drawbacks is the toxicity of TNT. During synthesis of TNT, undesirable isomers are produced. Without wishing to be bound by any theory, it is believed that meta isomers produced during the nitration of toluene react with the sodium sulfite to produce water-soluble, sulfated nitrotoluene that is red and highly tonic. Waste streams containing these isomers are known as red and pink water, and are considerably toxic and 68483-40(S) hazardous to workers and the environment. Consequently, stringent domestic environmental regulations have been imposed to protect worker safety and prevent against adverse ecological impact caused by the waste streams. However, waste stream clean up is laborious and expensive. These regulations and safety precautions have also increased manufacturing costs and slowed production rates, thereby making Tritonal and TNT production largely uneconomical and leading to cessation of domestic TNT production by most, if not all domestic manufacturers.
The generation of undesirable isomers during TNT
synthesis has the additional drawback of increasing the exudation of TNT from the ordnance. Many isomers generated during TNT synthesis have melting points lower than that of 'TNT. These isomers tend to exude under high storage temperature requirements, such as about 74°C (165°F). The exudation of TNT isomers from Tritonal raises concerns that the isomers might enter into areas of munitions that are not designed for exposure to energetic materials. In such an event, the sensitivity, vulnerability, and ability to handle and transport the munitions safely may be compromised.
SUMMARY OF THE INVENTION
This invention provides a Tritonal replacement composition that exhibits comparable energetic and pouring properties to Tritonal, in particular similar energies of detonation and melting points for melt-pouring procedures, but may be produced without as severe toxicity issues as encountered in TNT production and substantially without undesirable isomers that substantially lower the melting point of TNT and cause exudation.
68483-40 (S) This invention provides a Tritonal replacement that exhibits comparable energetic and pouring properties to Tritonal, but increases process safety by exhibiting substantially reduced shock sensitivity and/or either comparable or reduced thermal sensitivity compared to Tritonal. For example, reduced sensitivity of the Tritonal replacement may mean a lower vulnerability to physical and thermal stimuli such as, for example, bullet and fragment impact, fast and slow cook-off, and/or sympathetic detonation.
In accordance with the purposes of the invention as embodied and broadly described in this document, according to a first aspect of this invention there is provided a melt-pourable explosive composition comprising 30 weight percent to 70 weight percent of one or more organic binders selected from the group consisting of mononitro aromatics and dinitro aromatics, 5 weight percent to 35 weight percent of one or more oxidizer, and 5 weight percent to 35 weight percent of one or more reactive metallic fuels. The aromatic binder or collection of aromatic binders exhibit an energy of detonation that is lower than TNT and collectively have a total melting point in a range of 80°C to 115°C. The melt-pourable explosive composition is formulated to become melt-pourable at a temperature in the range of 80°C to 115°C.
In accordance with a second aspect of this invention, a melt-pourable explosive composition comprises 30 weight percent to 70 weight percent of one or more organic binders selected from the group consisting of mononitro aromatics and dinitro aromatics, 5 weight percent to 35 weight percent of one or more inorganic oxidizers, and 5 weight percent to 35 weight percent of one or more reactive metallic fuels, preferably aluminum. The organic 68483-40 (S) binder or collection of organic binders exhibit a total energy of detonation lower than TNT and collectively have a total melting point in a range of 80°C to 115°C. The inorganic oxidizers) preferably comprise at least one member selected from the group consisting of perchlorates and nitrates, and preferably have an average particle size of 3 to 60 microns, more preferably 5 to 20 microns. It is still more preferable that the mononitro/dinitro aromatic compound(s), the inorganic oxidizer(s), and the metallic fuels) collectively account for at least 95 weight percent, more preferably at least 99 weight percent of the total weight of the explosive composition. The composition is preferably essentially free of TNT. As in the case of the first aspect, in this second aspect the melt-pourable explosive composition is formulated to become melt-pourable at a temperature in a range of 80°C to 115°C.
In a particular aspect of the invention there is provided a melt-pourable explosive composition comprising: 30 weight percent to 70 weight percent of an organic binder comprising 2,4-dinitroanisole; 5 weight percent to 35 weight percent of at least one oxidizer; and 5 weight percent to 35 weight percent of at least one reactive metallic fuel, wherein the melt-pourable explosive composition is formulated to be pourable at a temperature in a range of 80°C to 115°C.
In accordance with the principles of this invention, the above and other aspects are attained by replacing a fundamental and well-accepted component of Tritonal, 2,4,6-trinitrotoluene, with one or more aromatic binders, each preferably having one or two nitro groups, more preferably nitrocarbon (C-NOZ) moieties, and an oxidizer, preferably an inorganic oxidizer. It has been discovered that mononitro and dinitro aromatics such as 68483-40 (S) dinitroanisole can be melt-poured without presenting the same degree of the toxicity drawbacks experienced with the use of TNT. Additionally, many mononitro and dinitro aromatics are lower in costs and more widely available than TNT. Mononitro and dinitro aromatics are less detonable than tri-nitrated aromatics. Therefore, the mononitro and dinitro aromatics do not require the explosive transportation, storage, and packaging infrastructure that tri-nitrated compounds, such as TNT, mandate.
Generally, the use of mononitro and dinitro aromatics in place of TNT in the Tritonal formulation has been disfavored (if not overlooked) in the melt-pouring art due to their low energetic oxygen content compared 4a to TNT. This drawback is overcome by the addition of oxidizer particles to the melt-pourable Tritonal replacement composition. The oxidizer particles are preferably inorganic, and preferably have relatively fine particle sizes. The oxidizer particles compensate for the energy loss experienced by the replacement of TNT with the less energetic mononitro andlor dinitro aromatic melt-pourable binders.
Additionally, the different melting points that mononitro and dinitro aromatics possess compared to TNT have also disfavored the melt-pourable binder substitution. Melt pouring requires heating of the binder to a temperature higher than its melting point, so that the binder can be mixed with the energetic filler, which is typically at ambient temperature, and poured by melting. A typical and useful melting point range for the melt or pour process is 80°C to 115°C. However, melt-pourable Tritonal replacement compositions should not be heated close to or above their exothermic decomposition temperatures, because exothermic decomposition may cause the Tritonal replacement composition to ignite automatically and generate an exothermic deflagration or explosion.
Preferably, a relatively wide "safety margin" is present between the melt temperature of the Tritonal replacement composition and the temperature at which the composition experiences an onset of exothermic decomposition. TNT has a melting point of about 80.9°C and is believed to experience an onset of exothermic decomposition at about 185°C, giving a relatively wide safety margin between the binder melting temperature and the autoignition temperature. On the other hand, many mononitro and dinitro aromatics have melting points exceeding that of TNT, thereby narrowing the safety margin for melt pouring. For example, dinitroanisole has a melting point of 94°C.
This drawback can be overcome by adding a processing aid to the melt-pourable Tritonal replacement composition. The processing aid is preferably also a mononitro or dinitro aromatic, and more preferably is selected from the group consisting of alkylnitroanilines and arylnitroanilines. The processing aid lowers the overall melting temperature of the energetic composition, preferably into a range of from 80°C to ll5°C, while preferably raising the onset of exothermic decomposition temperature, preferably to at least 5~°C higher than the melting temperature to widen the safety margin.
This invention is also directed to ordnances and munitions in which the melt-pourable Tritonal replacement composition of this invention can be used, including, by way of example, mortars, grenades, artillery shells, warheads, and antipersonnel mines.
These and other objects, aspects and advantages of the invention will be apparent to those skilled in the art upon reading the specification and appended claims, which explain the principles of this invention.
DETAILED DESCRTPTION OF PREFERRED EMBODIMENTS
AND METHODS OF THE INVENTION
Reference will now be made in detail to the presently preferred embodiments and methods of the invention. It should be noted, however, that the invention in its broader aspects is not limited to the specific details, representative devices and methods, and illustrative examples shown and described in this section in connection with the preferred embodiments and methods. The invention according to its various aspects is particularly pointed out and distinctly claimed in the attached claims read in view of this specification, and appropriate equivalents.
It is to be noted that, as used in the specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.
Generally, the melt-pourable binder or binders constitute 30 weight percent to 70 weight percent, more preferably 40 weight percent to 60 weight percent, of the total weight of the Tritonal replacement composition. It is preferred that the binder or binders include nitrocarbon (C-N02) moieties, although the nitro moieties may include nitramines (N-N02). Exemplary melt-pourable binders suitable for this invention include mononitro-substituted and dinitro-substituted phenyl alkyl ethers having the following formula:
RS Ri Ra Ra wherein one or two members selected from Ri, R~, Rs, R4, and Rs are nitro (-NO~) groups, the remaining of Rl to Rs are the same or different and are preferably selected from -H, -OH, -NHS, NR7Rs, an aryl group, or an -alkyl group (such as methyl), Rs is an alkyl group (preferably a methyl, ethyl, or propyl group), R7 is hydrogen or an alkyl or aryl group, and R$ is hydrogen or an alkyl group.
2,4-dinitroanisole (2,4-dinitrophenyl-methyl-ether) and 2,4 dinitrophenotole (2,4-dinitrophenyl-ethyl-ether) are examples of dinitro-substituted phenyl alkyl ethers suitable for use in the present melt-pourable explosive composition, while 4-methoxy-2-nitrophenol is an example of a preferred mononitro-substituted phenyl alkyl ether.
However, Tritonal has several drawbacks attributable to its TNT binder.
One of the most prominent of these drawbacks is the toxicity of TNT. During synthesis of TNT, undesirable isomers are produced. Without wishing to be bound by any theory, it is believed that meta isomers produced during the nitration of toluene react with the sodium sulfite to produce water-soluble, sulfated nitrotoluene that is red and highly tonic. Waste streams containing these isomers are known as red and pink water, and are considerably toxic and 68483-40(S) hazardous to workers and the environment. Consequently, stringent domestic environmental regulations have been imposed to protect worker safety and prevent against adverse ecological impact caused by the waste streams. However, waste stream clean up is laborious and expensive. These regulations and safety precautions have also increased manufacturing costs and slowed production rates, thereby making Tritonal and TNT production largely uneconomical and leading to cessation of domestic TNT production by most, if not all domestic manufacturers.
The generation of undesirable isomers during TNT
synthesis has the additional drawback of increasing the exudation of TNT from the ordnance. Many isomers generated during TNT synthesis have melting points lower than that of 'TNT. These isomers tend to exude under high storage temperature requirements, such as about 74°C (165°F). The exudation of TNT isomers from Tritonal raises concerns that the isomers might enter into areas of munitions that are not designed for exposure to energetic materials. In such an event, the sensitivity, vulnerability, and ability to handle and transport the munitions safely may be compromised.
SUMMARY OF THE INVENTION
This invention provides a Tritonal replacement composition that exhibits comparable energetic and pouring properties to Tritonal, in particular similar energies of detonation and melting points for melt-pouring procedures, but may be produced without as severe toxicity issues as encountered in TNT production and substantially without undesirable isomers that substantially lower the melting point of TNT and cause exudation.
68483-40 (S) This invention provides a Tritonal replacement that exhibits comparable energetic and pouring properties to Tritonal, but increases process safety by exhibiting substantially reduced shock sensitivity and/or either comparable or reduced thermal sensitivity compared to Tritonal. For example, reduced sensitivity of the Tritonal replacement may mean a lower vulnerability to physical and thermal stimuli such as, for example, bullet and fragment impact, fast and slow cook-off, and/or sympathetic detonation.
In accordance with the purposes of the invention as embodied and broadly described in this document, according to a first aspect of this invention there is provided a melt-pourable explosive composition comprising 30 weight percent to 70 weight percent of one or more organic binders selected from the group consisting of mononitro aromatics and dinitro aromatics, 5 weight percent to 35 weight percent of one or more oxidizer, and 5 weight percent to 35 weight percent of one or more reactive metallic fuels. The aromatic binder or collection of aromatic binders exhibit an energy of detonation that is lower than TNT and collectively have a total melting point in a range of 80°C to 115°C. The melt-pourable explosive composition is formulated to become melt-pourable at a temperature in the range of 80°C to 115°C.
In accordance with a second aspect of this invention, a melt-pourable explosive composition comprises 30 weight percent to 70 weight percent of one or more organic binders selected from the group consisting of mononitro aromatics and dinitro aromatics, 5 weight percent to 35 weight percent of one or more inorganic oxidizers, and 5 weight percent to 35 weight percent of one or more reactive metallic fuels, preferably aluminum. The organic 68483-40 (S) binder or collection of organic binders exhibit a total energy of detonation lower than TNT and collectively have a total melting point in a range of 80°C to 115°C. The inorganic oxidizers) preferably comprise at least one member selected from the group consisting of perchlorates and nitrates, and preferably have an average particle size of 3 to 60 microns, more preferably 5 to 20 microns. It is still more preferable that the mononitro/dinitro aromatic compound(s), the inorganic oxidizer(s), and the metallic fuels) collectively account for at least 95 weight percent, more preferably at least 99 weight percent of the total weight of the explosive composition. The composition is preferably essentially free of TNT. As in the case of the first aspect, in this second aspect the melt-pourable explosive composition is formulated to become melt-pourable at a temperature in a range of 80°C to 115°C.
In a particular aspect of the invention there is provided a melt-pourable explosive composition comprising: 30 weight percent to 70 weight percent of an organic binder comprising 2,4-dinitroanisole; 5 weight percent to 35 weight percent of at least one oxidizer; and 5 weight percent to 35 weight percent of at least one reactive metallic fuel, wherein the melt-pourable explosive composition is formulated to be pourable at a temperature in a range of 80°C to 115°C.
In accordance with the principles of this invention, the above and other aspects are attained by replacing a fundamental and well-accepted component of Tritonal, 2,4,6-trinitrotoluene, with one or more aromatic binders, each preferably having one or two nitro groups, more preferably nitrocarbon (C-NOZ) moieties, and an oxidizer, preferably an inorganic oxidizer. It has been discovered that mononitro and dinitro aromatics such as 68483-40 (S) dinitroanisole can be melt-poured without presenting the same degree of the toxicity drawbacks experienced with the use of TNT. Additionally, many mononitro and dinitro aromatics are lower in costs and more widely available than TNT. Mononitro and dinitro aromatics are less detonable than tri-nitrated aromatics. Therefore, the mononitro and dinitro aromatics do not require the explosive transportation, storage, and packaging infrastructure that tri-nitrated compounds, such as TNT, mandate.
Generally, the use of mononitro and dinitro aromatics in place of TNT in the Tritonal formulation has been disfavored (if not overlooked) in the melt-pouring art due to their low energetic oxygen content compared 4a to TNT. This drawback is overcome by the addition of oxidizer particles to the melt-pourable Tritonal replacement composition. The oxidizer particles are preferably inorganic, and preferably have relatively fine particle sizes. The oxidizer particles compensate for the energy loss experienced by the replacement of TNT with the less energetic mononitro andlor dinitro aromatic melt-pourable binders.
Additionally, the different melting points that mononitro and dinitro aromatics possess compared to TNT have also disfavored the melt-pourable binder substitution. Melt pouring requires heating of the binder to a temperature higher than its melting point, so that the binder can be mixed with the energetic filler, which is typically at ambient temperature, and poured by melting. A typical and useful melting point range for the melt or pour process is 80°C to 115°C. However, melt-pourable Tritonal replacement compositions should not be heated close to or above their exothermic decomposition temperatures, because exothermic decomposition may cause the Tritonal replacement composition to ignite automatically and generate an exothermic deflagration or explosion.
Preferably, a relatively wide "safety margin" is present between the melt temperature of the Tritonal replacement composition and the temperature at which the composition experiences an onset of exothermic decomposition. TNT has a melting point of about 80.9°C and is believed to experience an onset of exothermic decomposition at about 185°C, giving a relatively wide safety margin between the binder melting temperature and the autoignition temperature. On the other hand, many mononitro and dinitro aromatics have melting points exceeding that of TNT, thereby narrowing the safety margin for melt pouring. For example, dinitroanisole has a melting point of 94°C.
This drawback can be overcome by adding a processing aid to the melt-pourable Tritonal replacement composition. The processing aid is preferably also a mononitro or dinitro aromatic, and more preferably is selected from the group consisting of alkylnitroanilines and arylnitroanilines. The processing aid lowers the overall melting temperature of the energetic composition, preferably into a range of from 80°C to ll5°C, while preferably raising the onset of exothermic decomposition temperature, preferably to at least 5~°C higher than the melting temperature to widen the safety margin.
This invention is also directed to ordnances and munitions in which the melt-pourable Tritonal replacement composition of this invention can be used, including, by way of example, mortars, grenades, artillery shells, warheads, and antipersonnel mines.
These and other objects, aspects and advantages of the invention will be apparent to those skilled in the art upon reading the specification and appended claims, which explain the principles of this invention.
DETAILED DESCRTPTION OF PREFERRED EMBODIMENTS
AND METHODS OF THE INVENTION
Reference will now be made in detail to the presently preferred embodiments and methods of the invention. It should be noted, however, that the invention in its broader aspects is not limited to the specific details, representative devices and methods, and illustrative examples shown and described in this section in connection with the preferred embodiments and methods. The invention according to its various aspects is particularly pointed out and distinctly claimed in the attached claims read in view of this specification, and appropriate equivalents.
It is to be noted that, as used in the specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.
Generally, the melt-pourable binder or binders constitute 30 weight percent to 70 weight percent, more preferably 40 weight percent to 60 weight percent, of the total weight of the Tritonal replacement composition. It is preferred that the binder or binders include nitrocarbon (C-N02) moieties, although the nitro moieties may include nitramines (N-N02). Exemplary melt-pourable binders suitable for this invention include mononitro-substituted and dinitro-substituted phenyl alkyl ethers having the following formula:
RS Ri Ra Ra wherein one or two members selected from Ri, R~, Rs, R4, and Rs are nitro (-NO~) groups, the remaining of Rl to Rs are the same or different and are preferably selected from -H, -OH, -NHS, NR7Rs, an aryl group, or an -alkyl group (such as methyl), Rs is an alkyl group (preferably a methyl, ethyl, or propyl group), R7 is hydrogen or an alkyl or aryl group, and R$ is hydrogen or an alkyl group.
2,4-dinitroanisole (2,4-dinitrophenyl-methyl-ether) and 2,4 dinitrophenotole (2,4-dinitrophenyl-ethyl-ether) are examples of dinitro-substituted phenyl alkyl ethers suitable for use in the present melt-pourable explosive composition, while 4-methoxy-2-nitrophenol is an example of a preferred mononitro-substituted phenyl alkyl ether.
OCH~CH, OCHa H NOZ H NOZ H H
H H H H
H NOz 2,4-dinitroanisole (DNAN) 2,4-dinitrophenotole 4-methoxy-2-nitrophenol As referred to herein, aromatics include phenols and aryl amines.
For example, mononitro and dinitro aromatic binders suitable for use with this invention include nitrophenols, such as meta-nitrophenol, para-nitrophenol, and 2-amino-4-nitrophenol; dinitrophenols, such as 2,4-dinitrophenol and 4,6-dinitro-o-cresol; nitrotoluene and dinitrotoluenes, such as 2,4-dinitrotoluene; mononitroanilines, such as orth0-nitroaniline, meta-nitroaniline, para-nitroaniline; and dinitroanilines, such as 2,4-dinitroaniline and 2,6-dinitroaniline. As referred to herein, aromatics also include polycyclic benzenoid aromatics, such as mononitronaphthalenes and dinitronaphthalenes (e.g., 1,5-dinitronapthalene). It is also within the scope of the invention to use one or more heterocyclic binders, such as 4-chloro-7-nitrobenzofurazon, 5-nitro-2-furaldehyde diacetate, 5-nitro-isoquinoline, and methyl-5-nitro-2-furoate.
Other mononitro and dinitro aromatic binders that may be considered include the following:
4-nitrobe nzaldehyde;
4-nitroacetophenone;
H H H H
H NOz 2,4-dinitroanisole (DNAN) 2,4-dinitrophenotole 4-methoxy-2-nitrophenol As referred to herein, aromatics include phenols and aryl amines.
For example, mononitro and dinitro aromatic binders suitable for use with this invention include nitrophenols, such as meta-nitrophenol, para-nitrophenol, and 2-amino-4-nitrophenol; dinitrophenols, such as 2,4-dinitrophenol and 4,6-dinitro-o-cresol; nitrotoluene and dinitrotoluenes, such as 2,4-dinitrotoluene; mononitroanilines, such as orth0-nitroaniline, meta-nitroaniline, para-nitroaniline; and dinitroanilines, such as 2,4-dinitroaniline and 2,6-dinitroaniline. As referred to herein, aromatics also include polycyclic benzenoid aromatics, such as mononitronaphthalenes and dinitronaphthalenes (e.g., 1,5-dinitronapthalene). It is also within the scope of the invention to use one or more heterocyclic binders, such as 4-chloro-7-nitrobenzofurazon, 5-nitro-2-furaldehyde diacetate, 5-nitro-isoquinoline, and methyl-5-nitro-2-furoate.
Other mononitro and dinitro aromatic binders that may be considered include the following:
4-nitrobe nzaldehyde;
4-nitroacetophenone;
2-nitrobenzonitrile;
3-nitrobenzophenone;
4-nitrobenzyl alcohol;
4-nitrobenzyl bromide;
5-nitro-2-furaldehyde diacetate;
5-nitroisoquinoline;
4-nitrophenyl acetate;
2-nitrophenyl acetonitrile;
3-nitrophenyldisulfide;
4-nitrophenyl chloroformate;
1-(2-nitrophenyl)-1,2-ethanoldiol;
4-nitrophenyl trimethylacetate;
8-nitroquinoline;
2-nitro-4-(trifluoromethyl)aniline;
4-chloro-3-nitroacetophenone;
methyl-3-hydroxy-4-nitrobenzoate;
methyl-3-nitrobenzoate;
methyl-4-nitrobenzoate;
2-methyl-5-nitrobenzonitrile;
3-methyl-4-nitrobenzonitrile; and methyl-5-nitro-2-furoate.
The above examples of representative binders are not meant to be exhaustive. Rather, other aromatic binders may be suitable for this invention. Suitability of the binder is determined by balancing of various features and binder characteristics. For example, the binder preferably can be characterized by several or all of the following attributes: non-toxic, non-hygroscopic, non-mutagenic, light insensitive, air insensitive, non-corrosive, not a lachrymator, moisture insensitive, temperature insensitive between -54°C and 140°C, melting point between 80°C and 115°C, and viscosity of lower than 0.64 kp (kilopoise), more preferably lower than 0.16 kp within the pour temperature range of 80°C to 115°C.
The mononitro and dinitro aromatics generally have a much lower toxicity than TNT, particularly when the aromatics do not contain -OH
and/or -NHS functionalities. Thus, in many instances the use of mononitro and dinitro aromatics often simplifies handling and reduces the costs associated with manufacturing the Tritonal replacement explosive.
The processing aid of this invention preferably is a mononitro or dinitro aromatic, and more preferably is one or more N-alkyl-nitroanilines and/or N-aryl-nitroanilines having the following formula:
R5 Ri Ra Ra wherein Rs is hydrogen, R~ is an unsubstituted or substituted hydrocarbons (e.g., straight-chain alkyl, branched alkyl, cyclic alkyl, or to aryl group), and at least one of Ri to Rs is a vitro group, the remaining of Rl to Rs are the same or different and are preferably selected from -H, -OH, -NHs, NRaR9, an aryl group, or an -alkyl group (such as methyl), Rs is hydrogen or an alkyl or aryl group, and R9 is hydrogen or an alkyl group.
Exemplary N-alkyl-nitroaniline processing aids include the following:
H H H H
H H H H
NOZ NOZ
N-methyl-p-nitroaniline (MNA) N-ethyl-p-nitroaniline Examples of aryl-nitroaniline processing aids include the following:
N ~ ~ NOZ
H
H
4-nitrodiphenylamine 2-nitrodiphenylamine The concentration of the processing aid is selected in order to widen the "safety margin" at which the melt-pourable Tritonal replacement composition can be melt poured without significant threat of an onset of exothermic decomposition and auto-ignition of the Tritonal replacement composition. The processing aid preferably acts to lower the melting point of the composition towards (but not necessarily to) its eutectic point. By controlling the amount of the processing aid, the melting point of the mixture of binder and processing aid can be adjusted into a range of 80°C
to 115°C that generally characterizes melt-pourable materials. More preferably, the melting point is adjusted to 80°C to 110°C, more preferably 80°C to 90°C. Simultaneously, the processing aid preferably raises the temperature at which the composition experiences an onset of exothermic decomposition, thereby widening the safety margin between the melting temperature and the auto-ignition temperature of the Tritonal replacement composition.
The concentration of the processing aid can be selected by taking into account the amount of melt-pourable binder in the overall melt-pourable Tritonal replacement composition, the purity of the binder, and the nitrogen content of the binder. Generally, the Tritonal replacement composition can include, for example, from about 0.15 weight percent to about 1 weight percent processing aid based on the total weight of the Tritonal replacement composition. Using more than about 1 weight percent of the processing aid may lower the pour temperature of the melt-pourable Tritonal replacement composition below about 80°C.
Representative inorganic oxidizers suitable for the present melt-pourable Tritonal replacement composition include perchlorates, such. as potassium perchlorate, sodium perchlorate, strontium perchlorate, and ammonium perchlorate; and nitrates, such as potassium nitrate, sodium nitrate, strontium nitrate, ammonium nitrate, copper nitrate (Cu~(OH)sNOa), and hydroxylammonium nitrate (HAN); ammonium dinitramide (ADN); and hydrazinium nitroformate (HNF). Organic oxidizers having excess amounts of oxygen available for oxidizing the binder can also be used, although preferably the oxidizers consist of inorganic compounds. Examples of suitable organic oxidizers include nitramines, such as CL-20. In the event an organic oxidizer is used in the melt-pourable explosive composition, the organic oxidizer is preferably 68483-40 (S) present in less than 20 weight percent, more preferably less than 10 weight percent, still more preferably less than 5 weight percent, and most preferably no more than 1 weight percent based on the total weight of the explosive composition:
The oxidizer particles preferably having particle diameters, on average, 3 to 60 microns, more preferably 5 to 20 microns. It is possible to use bi-modal distributions, such as a combination of coarse particles (200 to 400 microns) and fine particles (less than 20). More preferred, however, is a single modal distribution of 5 to 50 microns. In the event that a single modal distribution in this particle size range is selected, the content of inorganic oxidizer in the energetic composition is preferably in a range of 15 weight percent to 20 weight percent.
Representative reactive metallic fuels that may be used in this invention include one or more of the following: aluminum, magnesium, boron, titanium, zirconium, and mixtures thereof Of these, aluminum is preferred. The particles may have an average particle size oi' for example, 3 to 60 microns, more preferably 5 to 20 microns. The metallic fuel preferably constitutes from 5 weight percent to 35 weight percent of the Tritonal replacement composition, more preferably 15 weight percent to 20 weight percent. Preferably, the inorganic oxidizer and metallic fuel are present in a weight ratio of about 1:1.
Preferably, the melt-pourable Tritonal replacement composition of this invention is substantially free of polymeric binders conventionally found in pressable and extrudable energetic materials, since an undue amount of these polymeric binders can lower the energy (especially for non-energetic polymer binders) and reduce the melt pourability (by increasing the viscosity) of the melt-pourable explosive.
A process of making the melt-pourable Tritonal replacement composition will now be described in more detail below. It should be 68483-40(S) understood that various modifications and alterations to the process and equipment described below are possible and encompassed by this invention.
The binder and optional processing aid are loaded into a pressurized, steam-heated melt kettle having a surrounding jacket. The kettle is heated to a temperature far enough above the melting temperature of the binder and processing aid to prevent solidification of the binder during the subsequent addition of ambient-temperature particles, but not so high as to cause an onset of exothermic decomposition. For example, the~kettle may be heated to about 90°C to 100°C, preferably 95°C. The oxidizer and fuel are then added by metering, i.e., adding the oxidizer and fuel either in stages or continuously so as not to lower the temperature of the melt phase below its melting temperature.
Preferably, the oxidizer is added prior to the fuel. Constant stirring is preferably performed throughout the mix cycle. Stirring is preferably sufficiently rapid to wet the oxidizer particles and achieve homogeneity in a relatively short time. : The mixture is then poured or cast, usually into a case of munitions or the like.
As mentioned above, the melt-pourable composition of preferred aspects of this invention exhibits comparable energetic and pouring properties to Tritonal, but increases process safety by exhibiting substantially reduced shock sensitivity compared to Z'ritonal.
An indicator of thermal stability is the temperature at which an explosive composition experiences an exotherm, or exothermic decomposition. A test known as Stimulated Bulk Autoignition Test, ox SBAT, .may be used to determine this temperature. Essentially, the SBAT
simulates the thermal response of,a large mass of energetic material using only a small quantity of material. The test sample is placed in Pyrez tube and insulated, and then placed in metal blocks in an oven. An identically insulated non-reactive sample, such as an aluminum block, is placed in 68483-40 (S) the oven along side of the test sample for temperature comparisons. The samples are heated from 38°C (100°F) to 260°C
(500°F) over a 16 hour pexiod at a rate of 13.3°Clhr (24°F/hr). The temperatures of the energetic material and control are monitored through thermocouples and recorded on a chart until the test is complete. The reaction is recorded along with the onset temperature, which is the temperature at which the data trace of the energetic material first leaves the baseline, i.e., that of the control.
Energetic materials with high autoignition temperatures are desirable because they are less likely to explode or detonate when exposed to elevated temperatures. The energetic composition of this invention preferably experiences an onset of thermal decomposition that is at least 55°C, more preferably at least 100°C, higher than the, temperature at which the energetic composition becomes melt pourable.
One test for measuring shock sensitivity is known in the art as the Large Scale Gap Tests (LSGT), in which a test material is placed into a metal tube on top of a witness plate. A predetermined number of PMMA (polymethylmethacrylate) cards are placed between the top of the metal tube and a booster material, which typically consists of 50 wt% PETN (pentaerythratol tetranitrate) and 50 wt9io TNT (trinitrotoluene), available as Pentoliter": The distance between the boostex and the metal tube is expressed in cards, where 1 card is equal to 0.0254 cm (0.01 inch), such that 100 cards equals 2.64 cm (1 inch). A card gap measurement is the minimum number of cards required to prevent the booster from detonating the explosive sample, so that the sample does not blow a hole through the witness plate. Thus, the lower the card value, the lower the shock sensitivity.
The LSGT (or NOL Card Pipe Test) is more fully described in Joint Technical Bulletin, Navy document number NAVSEA INST 8020.8B, Air 68483-40(S) Force technical order 11A-1-47, Defense Logistics Agency regulation DLAR 8220.1, and Army technical bulletin TB700-2.
Tritonal has a measured card gap value of 127. The explosive composition of this invention preferably has a card gap that is less than 127, more preferably less than 105, and still more preferably less than 85.
Energetic performance of an explosive can be evaluated through use of calculated properties, such as total energy of detonation, theoretical maximum density (T1VID), detonation pressure, shock velocity, cylinder expansion energy, and the like. These properties may be calculated based on the software CHEETAH, available through Lawrence Livermore National Laboratory of Livermore, Ca. This software is well known and used in the art, including by those having ordinary skill in the art of explosive development.
Tritonal has a total energy of detonation of 12.9 kJ/cc. In an especially preferred embodiment of this invention, the melt-pourable explosive composition has a total energy of detonation within 10 percent of 12.9 kJ/cc, i.e., 11.6 kJ/cc to 14.2 kJlcc.
A measurable property for determining energetic performance of an explosive is dent depth. Dent 'depth measurements are conducted by placing a 350 gram sample in a metal tube, identical to the one discussed above and used for the NOL card gap test, having exposed ends. The metal tube sits on a 1018 steel plate having a thickness of 5.08 cm (2 inches) and a width and height of 15.24 x 15.24 cm (6 x 6 inches), so that one of the ends of the tube is in contact with the steel plate. A Pentolite booster is placed on top of the metal tube and in operative association with the sample. The explosive is detonated in the pipe by activating the booster. The detonation products from the explosion form an indentation in the steel plate. The depth of this indentation is measured and recorded as the dent depth, which represents the amount of work performed by the explosive.
The dent depth of Tritonal is about 0.793 cm (0.312 inch). The dent depth of the explosive composition of this invention is preferably within 10 percent of that of Tritonal, a.e., 0.713 cm to 0.872 cm.
EXAMPLES
The following examples illustrate embodiments that have been made in accordance with the present invention. Also set forth are comparative examples prepared for comparison purposes. The inventive embodiments are not exhaustive or exclusive, but merely representative of the invention.
Unless otherwise indicated, all parts are by weight.
Example 1 In a pressurized, steam-heated melt kettle, dinitroanisole (DNAN) and N-methyl-p-nitroaniline (MNA) were introduced and heated above their melting temperature and stirred until melted and homogeneous. 50 micron ammonium perchlorate then 3 micron aluminum were metered into the kettle while maintaining constant stirring. The explosive composition was then melt poured onto a fl.aker and cooled at room temperature, and broken into small flake-like solid pieces, nominally 0.64 cm (0.25 inch) thick by 1.27 x 1.27 cm (0.5 x 0.5 inch). The f7.ake is then remelted in the melt kettle, and poured into the ordnance. The explosive composition comprised 49.75 weight percent DNAN, 0.25 weight percent MNA, 30 weight percent ammonium perchlorate, and 20 weight percent aluminum. When tested, the composition exhibited a dent depth of 0.808 cm, a card gap of less than 90, and an exotherm of 207°C.
Example 2 In a pressurized, steam-heated melt kettle, dinitroanisole (DNAN) and N-methyl-p-nitroaniline (MNA) were introduced and heated above their melting temperature and stirred until melted and homogeneous. 9 micron ammonium perchlorate and 3 micron aluminum were sequentially metered into the kettle while maintaining constant stirring. The explosive composition was then melt poured onto a flaker and cooled at room temperature, and broken into small flake-like solid pieces, nominally 0.64 cm (0.25 inch) thick by 1.27 x 1.27 cm (0.5 x 0.5 inch). The explosive composition comprised 49.75 weight percent DNAN, 0.25 weight percent MNA, 30 weight percent ammonium perchlorate, and 20 weight percent.
When tested, the composition exhibited a dent depth of 0.876 cm, a card gap of 40, and an exotherm of 209°C.
Example 3 In a pressurized, steam-heated melt kettle, dinitroanisole (DNAN) and N-methyl-p-nitroaniline (MNA) were introduced and heated above their melting temperature and stirred until melted and homogeneous. 50 micron ammonium perchlorate and 20 micron aluminum were metered into the kettle while maintaining constant stirring. The explosive composition was then melt poured onto a flaker and cooled at room temperature, and broken into small flake-like solid pieces, nominally 0.64 em (0.25 inch) thick by 1.27 x 1.27 cm (0.5 x 0.5 inch). The explosive composition comprised 49.75 weight percent DNAN, 0.25 weight percent MNA, 30 weight percent ammonium perchlorate, and 20 weight percent aluminum. When tested, the composition exhibited a dent depth of 0.785 cm, a card gap of 58, and an exotherm of 218°C.
Example 4 In a pressurized, steam-heated melt kettle, dinitroanisole (DNAN) and N-methyl-p-nitroaniline (MNA) were introduced and heated above their melting temperature and stirred until melted and homogeneous. 9 micron ammonium perchlorate and 20 micron aluminum were metered into the kettle while maintaining constant stirring. The explosive composition was then melt poured onto a flaker and cooled at room temperature, and broken into small flake-like solid pieces, nominally 0.64 cm (0.25 inch) thick by 1.27 x 1.27 cm (0.5 x 0.5 inch). The explosive composition comprised 49.75 weight percent DNAN, 0.25 weight percent MNA, 30 weight percent ammonium perchlorate, and 20 weight percent aluminum. When tested, the composition exhibited a dent depth of 0.84 cm, a card gap of 60, and an exotherm of 218°C.
Example 5 In a pressurized, steam-heated melt kettle, dinitroanisole (DNAN) and N-methyl-p-nitroaniline (MNA) were introduced and heated above their melting temperature and stirred until melted and homogeneous. 50 micron ammonium perchlorate particles and 3 micron aluminum particles were metexed into the kettle while maintaining constant stirring. The explosive composition was then melt poured onto a flaker and cooled at room temperature, and broken into small flake-like solid pieces, nominally 0.64 cm (0.25 inch) thick by 1.27 x 1.27 cm (0.5 x 0.5 inch). The explosive composition comprised 59.75 weight percent DNAN, 0.25 weight percent MNA, 17 weight percent ammonium perchlorate, 23 weight percent aluminum. When tested, the composition exhibited a dent depth of 0.792 cm, a card gap of less than 50, and an exotherm of 242°C.
Example 6 In a pressurized, steam-heated melt kettle, dinitroanisole (DNAN) and N-methyl-p-nitroaniline (MNA) were introduced and heated above their melting temperature and stirred until melted and homogeneous. 50 micron ammonium perchlorate particles and 20 micron aluminum particles were sequentially metered into the kettle while maintaining constant stirring. The explosive composition was then melt poured onto a fl.aker and cooled at room temperature, and broken into small flake-like solid pieces, nominally 0.64 cm (0.25 inch) thick by 1.27 x 1.27 cm (0.5 x 0.5 inch). The explosive composition comprised 59.75 weight percent DNAN, 0.25 weight percent MNA, 17 weight percent ammonium perchlorate, and 23 weight percent aluminum. When tested, the composition exhibited a dent depth of 0.747 cm, a card gap of 69, and an exotherm of 204°C.
Each of Examples 1 and 3-6 exhibited dent depths falling within 10 percent of the dent depth of Tritonal. Example 2 was outside the range by a negligible amount of 0.004 cm. Examples 1-6 also exhibited card gaps well below that of Tritonal.
The foregoing detailed description of the preferred embodiments of the invention has been provided for the purpose of explaining the principles of the invention and its practical application, thereby enabling others skilled in the art to understand the invention for various embodiments and with various modifications as are suited to the particular use contemplated. The foregoing detailed description is not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Modifications and equivalents will be apparent to practitioners skilled in this art and are encompassed within the spirit and scope of the appended claims.
3-nitrobenzophenone;
4-nitrobenzyl alcohol;
4-nitrobenzyl bromide;
5-nitro-2-furaldehyde diacetate;
5-nitroisoquinoline;
4-nitrophenyl acetate;
2-nitrophenyl acetonitrile;
3-nitrophenyldisulfide;
4-nitrophenyl chloroformate;
1-(2-nitrophenyl)-1,2-ethanoldiol;
4-nitrophenyl trimethylacetate;
8-nitroquinoline;
2-nitro-4-(trifluoromethyl)aniline;
4-chloro-3-nitroacetophenone;
methyl-3-hydroxy-4-nitrobenzoate;
methyl-3-nitrobenzoate;
methyl-4-nitrobenzoate;
2-methyl-5-nitrobenzonitrile;
3-methyl-4-nitrobenzonitrile; and methyl-5-nitro-2-furoate.
The above examples of representative binders are not meant to be exhaustive. Rather, other aromatic binders may be suitable for this invention. Suitability of the binder is determined by balancing of various features and binder characteristics. For example, the binder preferably can be characterized by several or all of the following attributes: non-toxic, non-hygroscopic, non-mutagenic, light insensitive, air insensitive, non-corrosive, not a lachrymator, moisture insensitive, temperature insensitive between -54°C and 140°C, melting point between 80°C and 115°C, and viscosity of lower than 0.64 kp (kilopoise), more preferably lower than 0.16 kp within the pour temperature range of 80°C to 115°C.
The mononitro and dinitro aromatics generally have a much lower toxicity than TNT, particularly when the aromatics do not contain -OH
and/or -NHS functionalities. Thus, in many instances the use of mononitro and dinitro aromatics often simplifies handling and reduces the costs associated with manufacturing the Tritonal replacement explosive.
The processing aid of this invention preferably is a mononitro or dinitro aromatic, and more preferably is one or more N-alkyl-nitroanilines and/or N-aryl-nitroanilines having the following formula:
R5 Ri Ra Ra wherein Rs is hydrogen, R~ is an unsubstituted or substituted hydrocarbons (e.g., straight-chain alkyl, branched alkyl, cyclic alkyl, or to aryl group), and at least one of Ri to Rs is a vitro group, the remaining of Rl to Rs are the same or different and are preferably selected from -H, -OH, -NHs, NRaR9, an aryl group, or an -alkyl group (such as methyl), Rs is hydrogen or an alkyl or aryl group, and R9 is hydrogen or an alkyl group.
Exemplary N-alkyl-nitroaniline processing aids include the following:
H H H H
H H H H
NOZ NOZ
N-methyl-p-nitroaniline (MNA) N-ethyl-p-nitroaniline Examples of aryl-nitroaniline processing aids include the following:
N ~ ~ NOZ
H
H
4-nitrodiphenylamine 2-nitrodiphenylamine The concentration of the processing aid is selected in order to widen the "safety margin" at which the melt-pourable Tritonal replacement composition can be melt poured without significant threat of an onset of exothermic decomposition and auto-ignition of the Tritonal replacement composition. The processing aid preferably acts to lower the melting point of the composition towards (but not necessarily to) its eutectic point. By controlling the amount of the processing aid, the melting point of the mixture of binder and processing aid can be adjusted into a range of 80°C
to 115°C that generally characterizes melt-pourable materials. More preferably, the melting point is adjusted to 80°C to 110°C, more preferably 80°C to 90°C. Simultaneously, the processing aid preferably raises the temperature at which the composition experiences an onset of exothermic decomposition, thereby widening the safety margin between the melting temperature and the auto-ignition temperature of the Tritonal replacement composition.
The concentration of the processing aid can be selected by taking into account the amount of melt-pourable binder in the overall melt-pourable Tritonal replacement composition, the purity of the binder, and the nitrogen content of the binder. Generally, the Tritonal replacement composition can include, for example, from about 0.15 weight percent to about 1 weight percent processing aid based on the total weight of the Tritonal replacement composition. Using more than about 1 weight percent of the processing aid may lower the pour temperature of the melt-pourable Tritonal replacement composition below about 80°C.
Representative inorganic oxidizers suitable for the present melt-pourable Tritonal replacement composition include perchlorates, such. as potassium perchlorate, sodium perchlorate, strontium perchlorate, and ammonium perchlorate; and nitrates, such as potassium nitrate, sodium nitrate, strontium nitrate, ammonium nitrate, copper nitrate (Cu~(OH)sNOa), and hydroxylammonium nitrate (HAN); ammonium dinitramide (ADN); and hydrazinium nitroformate (HNF). Organic oxidizers having excess amounts of oxygen available for oxidizing the binder can also be used, although preferably the oxidizers consist of inorganic compounds. Examples of suitable organic oxidizers include nitramines, such as CL-20. In the event an organic oxidizer is used in the melt-pourable explosive composition, the organic oxidizer is preferably 68483-40 (S) present in less than 20 weight percent, more preferably less than 10 weight percent, still more preferably less than 5 weight percent, and most preferably no more than 1 weight percent based on the total weight of the explosive composition:
The oxidizer particles preferably having particle diameters, on average, 3 to 60 microns, more preferably 5 to 20 microns. It is possible to use bi-modal distributions, such as a combination of coarse particles (200 to 400 microns) and fine particles (less than 20). More preferred, however, is a single modal distribution of 5 to 50 microns. In the event that a single modal distribution in this particle size range is selected, the content of inorganic oxidizer in the energetic composition is preferably in a range of 15 weight percent to 20 weight percent.
Representative reactive metallic fuels that may be used in this invention include one or more of the following: aluminum, magnesium, boron, titanium, zirconium, and mixtures thereof Of these, aluminum is preferred. The particles may have an average particle size oi' for example, 3 to 60 microns, more preferably 5 to 20 microns. The metallic fuel preferably constitutes from 5 weight percent to 35 weight percent of the Tritonal replacement composition, more preferably 15 weight percent to 20 weight percent. Preferably, the inorganic oxidizer and metallic fuel are present in a weight ratio of about 1:1.
Preferably, the melt-pourable Tritonal replacement composition of this invention is substantially free of polymeric binders conventionally found in pressable and extrudable energetic materials, since an undue amount of these polymeric binders can lower the energy (especially for non-energetic polymer binders) and reduce the melt pourability (by increasing the viscosity) of the melt-pourable explosive.
A process of making the melt-pourable Tritonal replacement composition will now be described in more detail below. It should be 68483-40(S) understood that various modifications and alterations to the process and equipment described below are possible and encompassed by this invention.
The binder and optional processing aid are loaded into a pressurized, steam-heated melt kettle having a surrounding jacket. The kettle is heated to a temperature far enough above the melting temperature of the binder and processing aid to prevent solidification of the binder during the subsequent addition of ambient-temperature particles, but not so high as to cause an onset of exothermic decomposition. For example, the~kettle may be heated to about 90°C to 100°C, preferably 95°C. The oxidizer and fuel are then added by metering, i.e., adding the oxidizer and fuel either in stages or continuously so as not to lower the temperature of the melt phase below its melting temperature.
Preferably, the oxidizer is added prior to the fuel. Constant stirring is preferably performed throughout the mix cycle. Stirring is preferably sufficiently rapid to wet the oxidizer particles and achieve homogeneity in a relatively short time. : The mixture is then poured or cast, usually into a case of munitions or the like.
As mentioned above, the melt-pourable composition of preferred aspects of this invention exhibits comparable energetic and pouring properties to Tritonal, but increases process safety by exhibiting substantially reduced shock sensitivity compared to Z'ritonal.
An indicator of thermal stability is the temperature at which an explosive composition experiences an exotherm, or exothermic decomposition. A test known as Stimulated Bulk Autoignition Test, ox SBAT, .may be used to determine this temperature. Essentially, the SBAT
simulates the thermal response of,a large mass of energetic material using only a small quantity of material. The test sample is placed in Pyrez tube and insulated, and then placed in metal blocks in an oven. An identically insulated non-reactive sample, such as an aluminum block, is placed in 68483-40 (S) the oven along side of the test sample for temperature comparisons. The samples are heated from 38°C (100°F) to 260°C
(500°F) over a 16 hour pexiod at a rate of 13.3°Clhr (24°F/hr). The temperatures of the energetic material and control are monitored through thermocouples and recorded on a chart until the test is complete. The reaction is recorded along with the onset temperature, which is the temperature at which the data trace of the energetic material first leaves the baseline, i.e., that of the control.
Energetic materials with high autoignition temperatures are desirable because they are less likely to explode or detonate when exposed to elevated temperatures. The energetic composition of this invention preferably experiences an onset of thermal decomposition that is at least 55°C, more preferably at least 100°C, higher than the, temperature at which the energetic composition becomes melt pourable.
One test for measuring shock sensitivity is known in the art as the Large Scale Gap Tests (LSGT), in which a test material is placed into a metal tube on top of a witness plate. A predetermined number of PMMA (polymethylmethacrylate) cards are placed between the top of the metal tube and a booster material, which typically consists of 50 wt% PETN (pentaerythratol tetranitrate) and 50 wt9io TNT (trinitrotoluene), available as Pentoliter": The distance between the boostex and the metal tube is expressed in cards, where 1 card is equal to 0.0254 cm (0.01 inch), such that 100 cards equals 2.64 cm (1 inch). A card gap measurement is the minimum number of cards required to prevent the booster from detonating the explosive sample, so that the sample does not blow a hole through the witness plate. Thus, the lower the card value, the lower the shock sensitivity.
The LSGT (or NOL Card Pipe Test) is more fully described in Joint Technical Bulletin, Navy document number NAVSEA INST 8020.8B, Air 68483-40(S) Force technical order 11A-1-47, Defense Logistics Agency regulation DLAR 8220.1, and Army technical bulletin TB700-2.
Tritonal has a measured card gap value of 127. The explosive composition of this invention preferably has a card gap that is less than 127, more preferably less than 105, and still more preferably less than 85.
Energetic performance of an explosive can be evaluated through use of calculated properties, such as total energy of detonation, theoretical maximum density (T1VID), detonation pressure, shock velocity, cylinder expansion energy, and the like. These properties may be calculated based on the software CHEETAH, available through Lawrence Livermore National Laboratory of Livermore, Ca. This software is well known and used in the art, including by those having ordinary skill in the art of explosive development.
Tritonal has a total energy of detonation of 12.9 kJ/cc. In an especially preferred embodiment of this invention, the melt-pourable explosive composition has a total energy of detonation within 10 percent of 12.9 kJ/cc, i.e., 11.6 kJ/cc to 14.2 kJlcc.
A measurable property for determining energetic performance of an explosive is dent depth. Dent 'depth measurements are conducted by placing a 350 gram sample in a metal tube, identical to the one discussed above and used for the NOL card gap test, having exposed ends. The metal tube sits on a 1018 steel plate having a thickness of 5.08 cm (2 inches) and a width and height of 15.24 x 15.24 cm (6 x 6 inches), so that one of the ends of the tube is in contact with the steel plate. A Pentolite booster is placed on top of the metal tube and in operative association with the sample. The explosive is detonated in the pipe by activating the booster. The detonation products from the explosion form an indentation in the steel plate. The depth of this indentation is measured and recorded as the dent depth, which represents the amount of work performed by the explosive.
The dent depth of Tritonal is about 0.793 cm (0.312 inch). The dent depth of the explosive composition of this invention is preferably within 10 percent of that of Tritonal, a.e., 0.713 cm to 0.872 cm.
EXAMPLES
The following examples illustrate embodiments that have been made in accordance with the present invention. Also set forth are comparative examples prepared for comparison purposes. The inventive embodiments are not exhaustive or exclusive, but merely representative of the invention.
Unless otherwise indicated, all parts are by weight.
Example 1 In a pressurized, steam-heated melt kettle, dinitroanisole (DNAN) and N-methyl-p-nitroaniline (MNA) were introduced and heated above their melting temperature and stirred until melted and homogeneous. 50 micron ammonium perchlorate then 3 micron aluminum were metered into the kettle while maintaining constant stirring. The explosive composition was then melt poured onto a fl.aker and cooled at room temperature, and broken into small flake-like solid pieces, nominally 0.64 cm (0.25 inch) thick by 1.27 x 1.27 cm (0.5 x 0.5 inch). The f7.ake is then remelted in the melt kettle, and poured into the ordnance. The explosive composition comprised 49.75 weight percent DNAN, 0.25 weight percent MNA, 30 weight percent ammonium perchlorate, and 20 weight percent aluminum. When tested, the composition exhibited a dent depth of 0.808 cm, a card gap of less than 90, and an exotherm of 207°C.
Example 2 In a pressurized, steam-heated melt kettle, dinitroanisole (DNAN) and N-methyl-p-nitroaniline (MNA) were introduced and heated above their melting temperature and stirred until melted and homogeneous. 9 micron ammonium perchlorate and 3 micron aluminum were sequentially metered into the kettle while maintaining constant stirring. The explosive composition was then melt poured onto a flaker and cooled at room temperature, and broken into small flake-like solid pieces, nominally 0.64 cm (0.25 inch) thick by 1.27 x 1.27 cm (0.5 x 0.5 inch). The explosive composition comprised 49.75 weight percent DNAN, 0.25 weight percent MNA, 30 weight percent ammonium perchlorate, and 20 weight percent.
When tested, the composition exhibited a dent depth of 0.876 cm, a card gap of 40, and an exotherm of 209°C.
Example 3 In a pressurized, steam-heated melt kettle, dinitroanisole (DNAN) and N-methyl-p-nitroaniline (MNA) were introduced and heated above their melting temperature and stirred until melted and homogeneous. 50 micron ammonium perchlorate and 20 micron aluminum were metered into the kettle while maintaining constant stirring. The explosive composition was then melt poured onto a flaker and cooled at room temperature, and broken into small flake-like solid pieces, nominally 0.64 em (0.25 inch) thick by 1.27 x 1.27 cm (0.5 x 0.5 inch). The explosive composition comprised 49.75 weight percent DNAN, 0.25 weight percent MNA, 30 weight percent ammonium perchlorate, and 20 weight percent aluminum. When tested, the composition exhibited a dent depth of 0.785 cm, a card gap of 58, and an exotherm of 218°C.
Example 4 In a pressurized, steam-heated melt kettle, dinitroanisole (DNAN) and N-methyl-p-nitroaniline (MNA) were introduced and heated above their melting temperature and stirred until melted and homogeneous. 9 micron ammonium perchlorate and 20 micron aluminum were metered into the kettle while maintaining constant stirring. The explosive composition was then melt poured onto a flaker and cooled at room temperature, and broken into small flake-like solid pieces, nominally 0.64 cm (0.25 inch) thick by 1.27 x 1.27 cm (0.5 x 0.5 inch). The explosive composition comprised 49.75 weight percent DNAN, 0.25 weight percent MNA, 30 weight percent ammonium perchlorate, and 20 weight percent aluminum. When tested, the composition exhibited a dent depth of 0.84 cm, a card gap of 60, and an exotherm of 218°C.
Example 5 In a pressurized, steam-heated melt kettle, dinitroanisole (DNAN) and N-methyl-p-nitroaniline (MNA) were introduced and heated above their melting temperature and stirred until melted and homogeneous. 50 micron ammonium perchlorate particles and 3 micron aluminum particles were metexed into the kettle while maintaining constant stirring. The explosive composition was then melt poured onto a flaker and cooled at room temperature, and broken into small flake-like solid pieces, nominally 0.64 cm (0.25 inch) thick by 1.27 x 1.27 cm (0.5 x 0.5 inch). The explosive composition comprised 59.75 weight percent DNAN, 0.25 weight percent MNA, 17 weight percent ammonium perchlorate, 23 weight percent aluminum. When tested, the composition exhibited a dent depth of 0.792 cm, a card gap of less than 50, and an exotherm of 242°C.
Example 6 In a pressurized, steam-heated melt kettle, dinitroanisole (DNAN) and N-methyl-p-nitroaniline (MNA) were introduced and heated above their melting temperature and stirred until melted and homogeneous. 50 micron ammonium perchlorate particles and 20 micron aluminum particles were sequentially metered into the kettle while maintaining constant stirring. The explosive composition was then melt poured onto a fl.aker and cooled at room temperature, and broken into small flake-like solid pieces, nominally 0.64 cm (0.25 inch) thick by 1.27 x 1.27 cm (0.5 x 0.5 inch). The explosive composition comprised 59.75 weight percent DNAN, 0.25 weight percent MNA, 17 weight percent ammonium perchlorate, and 23 weight percent aluminum. When tested, the composition exhibited a dent depth of 0.747 cm, a card gap of 69, and an exotherm of 204°C.
Each of Examples 1 and 3-6 exhibited dent depths falling within 10 percent of the dent depth of Tritonal. Example 2 was outside the range by a negligible amount of 0.004 cm. Examples 1-6 also exhibited card gaps well below that of Tritonal.
The foregoing detailed description of the preferred embodiments of the invention has been provided for the purpose of explaining the principles of the invention and its practical application, thereby enabling others skilled in the art to understand the invention for various embodiments and with various modifications as are suited to the particular use contemplated. The foregoing detailed description is not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Modifications and equivalents will be apparent to practitioners skilled in this art and are encompassed within the spirit and scope of the appended claims.
Claims (18)
1. A melt-pourable explosive composition comprising:
30 weight percent to 70 weight percent of an organic binder comprising 2,4-dinitroanisole;
weight percent to 35 weight percent of at least one oxidizer; and 5 weight percent to 35 weight percent of at least one reactive metallic fuel, wherein the melt-pourable explosive composition is formulated to be pourable at a temperature in a range of 80°C to 115°C.
30 weight percent to 70 weight percent of an organic binder comprising 2,4-dinitroanisole;
weight percent to 35 weight percent of at least one oxidizer; and 5 weight percent to 35 weight percent of at least one reactive metallic fuel, wherein the melt-pourable explosive composition is formulated to be pourable at a temperature in a range of 80°C to 115°C.
2. The melt-pourable explosive composition of claim 1, further comprising an N-alkyl-nitroaniline as a processing aid.
3. The melt-pourable explosive composition of claim 1, further comprising N-methyl-nitroaniline as a processing aid.
4. The melt-pourable explosive composition of claim 1, further comprising an N-aryl-nitroaniline as a processing aid.
5. The melt-pourable explosive composition of claim 1, further comprising at least one processing aid selected from the group consisting of N-alkyl nitroaniline and N-aryl-nitroaniline, the at least one processing aid present at no more than 1 weight percent of the melt-pourable explosive composition.
6. The melt-pourable explosive composition of any one of claims 1 to 5, wherein the at least one reactive metallic fuel comprises aluminum.
7. The melt-pourable explosive composition of any one of claims 1 to 6, wherein the melt-pourable explosive composition undergoes an onset of thermal decomposition at a temperature that is at least 55.5°C higher than the temperature at which the melt-pourable explosive composition is formulated to be pourable.
8. The melt-pourable explosive composition of any one of claims 1 to 7, wherein the melt-pourable explosive composition exhibits a card gap of less than 105.
9. The melt-pourable explosive composition of claim 7, wherein the melt-pourable explosive composition exhibits a card gap of less than 85.
10. The melt-pourable explosive composition of any one of claims 1 to 9, wherein the melt-pourable explosive composition has a total energy of detonation of 11.6 kJ/cc to 14.2 kJ/cc.
11. The melt-pourable explosive composition of any one of claims 1 to 8, wherein the at least one oxidizer is at least one inorganic oxidizer.
12. The melt-pourable explosive composition of claim 11, wherein the at least one inorganic oxidizer comprises at least one member selected from the group consisting of a perchlorate and a nitrate.
13. The melt-pourable explosive composition of claim 12, wherein the perchlorate is selected from the group consisting of ammonium perchlorate, sodium perchlorate and potassium perchlorate.
14. The melt-pourable explosive composition of claim 12, wherein the nitrate is selected from the group consisting of ammonium nitrate, sodium nitrate, strontium nitrate and potassium nitrate.
15. The melt-pourable explosive composition of any one of claims 11 to 14, wherein the at least one inorganic oxidizer has an average particle size of 3 microns to 60 microns.
16. The melt-pourable explosive composition of claim 15, wherein the at least one inorganic oxidizer has an average particle size of 5 microns to 20 microns.
17. The melt-pourable explosive composition of any one of claims 1 to 16, wherein at least 99 weight percent of the melt-pourable explosive composition comprises a combination of the organic binder, the at least one inorganic oxidizer, and the at least one reactive metallic fuel.
18. The melt-pourable explosive composition of any one of claims 1 to 17, wherein the melt-pourable explosive composition exhibits a dent depth in a range of 0.713 cm to 0.872 cm.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/US2001/021046 WO2003002485A1 (en) | 2001-06-27 | 2001-06-27 | Reduced sensitivity, melt-pourable tritonal replacements |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2451760A1 CA2451760A1 (en) | 2003-01-09 |
| CA2451760C true CA2451760C (en) | 2006-08-15 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002451760A Expired - Fee Related CA2451760C (en) | 2001-06-27 | 2001-06-27 | Reduced sensitivity, melt-pourable tritonal replacements |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP1399399A1 (en) |
| CA (1) | CA2451760C (en) |
| WO (1) | WO2003002485A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102005044910B3 (en) | 2005-09-14 | 2007-03-15 | Jena-Optronik Gmbh | Schiefspiegler telescope with three mirror surfaces |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR349635A (en) * | 1904-04-05 | 1904-06-07 | Charles Girard | Improvements to explosives |
| FR465082A (en) * | 1913-11-20 | 1914-04-07 | Ivan Basil Tarnowski Von Tarno | Improvements in explosives |
| US3178325A (en) * | 1961-02-28 | 1965-04-13 | Jr Edwin M Scott | Metal nitrate explosives containing mononitrated aromatic sensitizing agents |
| GB1605421A (en) * | 1970-02-11 | 1998-11-18 | Colin George Lawson | Improvements in or relating to stabilisers for propellants |
| US4944816A (en) * | 1976-03-26 | 1990-07-31 | The United States Of America As Represented By The Secretary Of The Army | Ultra-ultrahigh burning rate composite modified double-base propellants containing porous ammonium perchlorate |
| US5949016A (en) * | 1991-07-29 | 1999-09-07 | The United States Of America As Represented By The Secretary Of The Navy | Energetic melt cast explosives |
| US5411615A (en) * | 1993-10-04 | 1995-05-02 | Thiokol Corporation | Aluminized eutectic bonded insensitive high explosive |
| JPH0859384A (en) * | 1994-08-12 | 1996-03-05 | Mitsubishi Chem Corp | Explosives |
| SE511285C2 (en) * | 1997-04-29 | 1999-09-06 | Foersvarets Forskningsanstalt | Melt-cast charges |
| US5997668A (en) * | 1998-07-27 | 1999-12-07 | The United States Of America As Represented By The Secretary Of The Air Force | Castable TNAZ/nitroaromaticamine composite explosive |
-
2001
- 2001-06-27 WO PCT/US2001/021046 patent/WO2003002485A1/en active Application Filing
- 2001-06-27 CA CA002451760A patent/CA2451760C/en not_active Expired - Fee Related
- 2001-06-27 EP EP01950810A patent/EP1399399A1/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| WO2003002485A1 (en) | 2003-01-09 |
| CA2451760A1 (en) | 2003-01-09 |
| EP1399399A1 (en) | 2004-03-24 |
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